Tropical Storm Bill continues strengthening
Tropical Storm Bill continues to gather strength in the middle Atlantic Ocean, and appears poised to become a major Cape Verdes-type hurricane later this week. Water vapor satellite loops show that Bill has developed a core region of heavy thunderstorms that should be fairly impervious to the dry Saharan air to its northwest, and the storm should be able to start building an eyewall tonight.
Wind shear is low, 5 - 10 knots, and is forecast to be in the low range for the next three days. With Sea Surface Temperatures at 27.5°C, and ocean heat content sharply increasing 2 - 3 days from now, Bill should be able to intensify to a major Category 3 or 4 hurricane by Wednesday. At that time, some increasing shear may limit further intensification.
The big news is that our most reliable computer model from last year--the ECMWF model--appears to have made the right call yesterday, forecasting that a major trough of low pressure would develop along the U.S. East Coast, turning Bill more to the north. All of the other models have now jumped on the ECMWF bandwagon, forecasting that Bill will pass well north of the Lesser Antilles Islands. The UKMET model, which was resisting forecasting the northward turn, has now joined the other models in its latest 12Z run. The main drama with Bill this week will be to see how close it passes to Bermuda. Several models have Bill passing within 200 miles of Bermuda on Saturday. It is too early to be confident that Bill will miss the U.S. East Coast.
